Technology to specify a faulty section of an optical fiber is generally known. A technology to specify a faulty section of an optical fiber is disclosed in the following PTL 1. FIG. 1 is a diagram for describing a structure and an operation of an optical pulse reflectometer of PTL 1.
The optical pulse reflectometer of PTL 1 is connected to an optical fiber line as illustrated in the upper diagram of FIG. 1. A plurality of light reflection elements P1, P2, . . . Pn that perform reflection of only a specific wavelength signal of a fixed amount are inserted into the optical fiber line. As indicated in the lower diagram of FIG. 1, the optical pulse reflectometer of PTL 1 transmits a specific wavelength signal (a light signal of a specific wavelength λ1) to the optical fiber line, and measures the level of reflected light at each predetermined time when reflected light from each light reflection element would reach. Reflected light from each light reflection element is reflected light of the same wavelength λ1. About a time in which reflected light of a predetermined level has not been detected due to a failure existing in the optical fiber, the optical pulse reflectometer of PTL 1 identifies that a failure has occurred in a position up to the position where a light reflection element corresponding to the time is inserted. About a time in which reflected light of a predetermined level has been detected, the optical pulse reflectometer of PTL 1 supposes that there are no failures up to the position where a light reflection element corresponding to the time is inserted.
As indicated by the aforementioned constitution and the operations, the optical pulse reflectometer of PTL 1 can specify a faulty section of an optical fiber.